For ease of discussion herein, this text frequently refers to capturing, storing or delivering “cold”, meaning the absence of heat. As such, “collecting cold to store in a heat sink” simply means removing heat energy from a heat sink, so that it can accept heat energy at a later time.
There are several established methods of heating and cooling homes and buildings. All of these systems represent a significant expense for businesses and residences when the initial cost and operating costs are combined. Heating oil, gas and electricity make up the bulk of energy we use for this purpose, and there are well known problems associated with our massive use of these fuels, including the expense, pollution, safety, and contribution to trade deficits and international political problems. Furthermore, summer air conditioning pushes peak demand to levels that strain our electric utilities and cause blackouts.
Efforts to solve these problems have focused on improving the systems already in place, instead of first seriously questioning the basic validity of systems that has created all these problems. Efforts are focused on improving furnace and central air conditioner efficiency, severely restricting refrigerant use, improving building methods to seal air leaks, etc.
But many of these efforts, even those perceived as successful, have downsides—some of which are generally unrecognized. For example, restricting refrigerant use ultimately expands government and regulatory bureaucracy and adds cost for consumers and taxpayers. Sealing air leaks makes indoor environments stale and less healthy.
As concern grows about energy cost and long term supplies, the inefficiencies of the established methods are more troubling. It seems wiser to collect and store free energy from the sun for use when it is needed.
For decades there have been numerous attempts to store the sun's energy on a relatively small scale. There are photovoltaic cells to make electricity. There are solar water heaters, passive solar building materials that absorb heat during the day and release it at night, and windows and skylights that can adjust to let more or less sunlight in. Over the years, innovations have generally increased the efficiency and lowered cost of these alternative systems, which may someday become widely accepted by consumers. But as of yet, none of them adequately address the seasonal needs of home and building heating and cooling.
Geothermal systems have operational cost advantages over more common systems, but still use considerable energy and are more expensive to install, which is one reason they are not prevalent after so many years on the market.
U.S. Pat. No. 5,435,380 describes a heat storage system, but uses tanks of water to store waste heat from incinerators and subway trains for later use. For long term storage of weather extremes, this has many shortcomings. It does not adequately isolate and insulate the heat and cold for such long-term storage, and its tanks would be too expensive for most residential customers. This patent belongs to Hitachi Plant Engineering & Construction Co, and may be effective for such industrial applications, but small business or residential customers may not like the idea of a water tank the size of their basement sitting in their entire back yard or just under the surface.
U.S. Pat. No. 5,941,238 describes a system for collecting and storing heat for use in heating water for home use or heating the home itself, using fluid stored in tanks made of old tires.
U.S. Pat. No. 4,350,200 describes a system that uses ducts throughout the walls, floors and roof rafters to circulate air for collecting heat and transporting it directly to water tanks for storage. This requires fundamental changes in building construction.
None of these systems collect heat in the extremes of summer to store it for use in winter when it is needed most. Furthermore, none of these systems collect “cold” in the extremes of winter and store it for use in summer when it is needed most. Such a system would need to have a large heat sink that is well insulated and poses no real or perceived danger or threat to residential customers. The established methods do not attempt this. Accordingly, it would be advantageous to provide a heat sink constructed with insulated successively hotter layers within each other.
Such a system would also need a controller designed to monitor conditions and direct the collection of heat or cold at the right time and in the method appropriate to the current weather situation, considering current storage levels and expected future needs and future losses. The established methods do not attempt this.
The system of U.S. Pat. No. 4,350,200 also uses a roof heat collection system radically different from conventional construction, including hollow extruded concrete plank beams and aluminum fins embedded in roofing tiles to conduct heat. Again this requires fundamental changes in building construction.
To become widely accepted, a system is needed that can operate very inexpensively without changing the fundamental ways buildings are constructed.
In its discussion of prior art, U.S. Pat. No. 6,681,593 mentions the need for a system of storing heat or cold from one season to the next, and mentions one previous proposal to do so by means of freezing and thawing a large pool of water. This prior art discussion claims two problems with this system: First, that it requires an equal number of heating degree days and cooling degree days, and second that the freezing process creates unmanageable problems with expansion of the pool, including damage to the reservoir walls. This method also has the previously mentioned problems associated with large expensive tanks of fluid that many residences and businesses would not want around.
U.S. Pat. No. 6,450,247 describes a system for cooling a building by using fluid circulated through a deep well (as with some geothermal systems) to cool the building without a compressor. This heats the earth around the well, so the system has additional pipes to assist the earth in dissipating that heat during the winter. This system is only designed for cooling, not heating a home. Furthermore, A-coils are commonly run at lower temperatures than the surrounding earth, so unless it is built on a very large scale, this system will be inadequate where seasonal cooling needs are great, and it will get worse as the summer cooling season wears on, and the earth around the well warms.
Accordingly, a system is needed for collecting and storing heat or cold for lengthy periods of time for later use in the heating or cooling needs of a building or residence.